The foregoing patents and patent applications are all directed to methods and apparatus for ameliorating the deterioration of coffee by substantially reducing both the oxidation and evaporation of the same. The entire disclosures of the aforesaid patents and applications are herein incorporated by reference.
If freshly brewed coffee be totally sealed with respect to atmosphere it will remain fresh indefinitely. This, of course, is not practical from the standpoint of conventional usage. Accordingly, the desire is to approach the state of total sealing of the coffee while yet being able to dispense the same in conventional fashion that requires no manipulative steps in addition to those required to pour from any conventional coffee pot. This has been achieved, in the past, by substantially sealing the open mouth of the coffee pot and dispensing coffee therefrom through a pour spout which opens into the pot immediately adjacent the bottom thereof so that one, in effect, pours from the bottom of the pot. The coffee within the pour spout acts as a liquid seal to protect the remainder of the coffee in the pot from atmospheric exposure through the pour spout. In order to dispense coffee from a substantially sealed pot there must be some means of maintaining atmospheric pressure on the coffee so that a vacuum lock does not prevent pouring. In the past this has been achieved either by the use of a flexible follower or restricted vent means of such restricted area that the greater vapor pressure of the hot coffee contained within the pot exceeds atmospheric pressure so that air does not enter the restricted vent means except during that time when coffee is actually being dispensed. Thus, in the case of a ten-cup coffee maker, for example, only ten cups of air are indrawn to the pot over that period of time until the entire pot is emptied which ten cup volume of air is negligible as compared with the normal large influx of air that takes place in a conventional, unsealed coffee pot.
Prior substantially sealed coffee pots which employ an outside pour spout opening into the bottom of the pot have been successful in function but expensive to manufacture. About the only practical method of making such a coffee pot with an outside pour spout is by slip casting porcelain material. This is expensive and production rates are low. The usual method of coffee pot manufacture in the United States involves blown borosilicate glass. This is by far the most economical method of manufacture and literally thousands of pieces per hour can be manufactured with relatively inexpensive tooling. Blown borosilicate glass, however, can only be produced in a shape that is rotationally symmetrical because of the manner in which the glass must be removed from the molds. For this reason, a coffee pot with an outside pour spout cannot be made from blown borosilicate glass.
Other efforts to take advantage of the use of a liquid seal in a pour spout extending to the bottom of a pot while constructing the pot from blown borosilicate glass have involved the use of a long pour spout extending down from a top assembly inside the glass pot. This works well in the case of a glass pot having cylindrical side walls whereby the downwardly extending pour spout can rest adjacent one side wall so that all of the coffee can be dispensed from the pot. Unfortunately, the usual design for glass coffee pots is to have an enlarged lower end so that a great deal of the coffee can not be dispensed through an inside pour spout as the coffee level lowers. Accordingly, to make use of an inside pour spout requires special tooling and the use of a special, cylindrically shaped pot to achieve the desired objective of reducing oxidation and evaporation.